Bioidentical vs Conventional HRT: What Women Actually Need to Know
Bioidentical and conventional HRT are often portrayed as opposites. Learn what the terms actually mean, where they overlap, and what the evidence says.
The terminology is more confusing than it needs to be
The terms bioidentical and conventional HRT are used frequently in discussions about menopause management, but they are often poorly defined and used in ways that create unnecessary confusion. Bioidentical simply means that the hormone is chemically identical to the hormone produced naturally in the human body. Conventional HRT, as used colloquially, usually refers to regulated pharmaceutical preparations that may contain bioidentical hormones, non-bioidentical hormones, or both. The distinction that actually matters clinically is not bioidentical versus conventional, but rather regulated versus compounded, standardised versus individualised, and well-studied versus less-studied. Understanding these practical differences helps women make informed choices with their doctors.
What regulated HRT contains
Most regulated HRT products prescribed in the UK, Europe, the US, and Australia already contain bioidentical hormones. Estradiol patches, gels, sprays, and many oral forms contain 17-beta estradiol, which is chemically identical to the estrogen produced by the ovaries. Micronised progesterone, sold under brand names such as Utrogestan and Prometrium, is also bioidentical, being chemically identical to human progesterone. These products have been through clinical trials, have consistent dosing, and are subject to regulatory oversight for quality, purity, and labelling. So when a woman's doctor prescribes an estradiol patch and micronised progesterone, she is already receiving bioidentical hormones in a regulated form.
What compounded bioidentical HRT is
Compounded bioidentical HRT refers to hormone preparations made to individual prescriptions by compounding pharmacies, often marketed on the basis of customisation to a woman's unique hormone profile. These preparations commonly contain hormones such as estriol and sometimes DHEA in addition to estradiol and progesterone. Compounded preparations are not subject to the same regulatory approval process as pharmaceutical products. Their hormone content, purity, and consistency vary between batches and between pharmacies. Blood or saliva hormone testing is often used to guide compounding, but these tests have not been validated as a reliable basis for hormone prescribing, and most major endocrinology and menopause organisations do not recommend compounded HRT as a first-line choice.
The safety evidence compared
Regulated estradiol and micronised progesterone have a body of clinical evidence behind them. Studies show that transdermal estradiol does not increase the risk of blood clots in the way that oral synthetic estrogens do, and that micronised progesterone has a more favourable cardiovascular and breast tissue profile than synthetic progestogens like medroxyprogesterone acetate. Compounded preparations, by contrast, lack equivalent long-term safety data. Because their hormone content varies, the risks associated with them are harder to quantify. The concern is not that compounded hormones are inherently dangerous, but that without consistent quality control, women cannot be confident they are receiving what the label says in the dose expected.
The appeal of compounded HRT and why women seek it
Women who are drawn to compounded bioidentical HRT are often motivated by a desire for a more personalised approach, dissatisfaction with standard options, or the belief that natural is safer. These are understandable motivations, particularly for women who have had side effects from synthetic progestogens or who have not found symptom relief with standard formulations. Some women prefer the idea of having their hormones measured and matched to their individual levels. However, hormone levels fluctuate significantly across the day and cycle, meaning a single test is not a reliable guide, and the claim that compounding produces a perfectly tailored dose is not well supported by the evidence.
Where regulated HRT falls short and what to do
Regulated HRT is not without its limitations. Not all women tolerate synthetic progestogens, and options may be limited in some healthcare systems. Dose flexibility can be restricted in standard formulations, and some women require combinations not readily available in a single product. In these cases, discussing specific regulated alternatives rather than moving immediately to compounding is worth doing. Options such as micronised progesterone combined with estradiol gel or patch, the Mirena IUS to deliver progestogen locally with systemic estrogen, or licensed testosterone preparations are all regulated approaches with more supporting evidence.
Making the decision that is right for you
The most important consideration when choosing between HRT options is making an informed decision based on accurate information rather than marketing language. If a practitioner offers compounded bioidentical HRT, ask what evidence they are using to guide dosing, what quality assurance the pharmacy has, and what monitoring they will provide. If you are using regulated HRT and experiencing issues, ask specifically about micronised progesterone if you are on a synthetic progestogen, or about trying a different delivery method. Tracking your symptoms consistently over weeks using PeriPlan helps you and your prescriber evaluate what is and is not working, which is the most useful information in any HRT conversation.
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